From 441d367644e2f60b37f36bfc656deee551acba5b Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 5 Jun 2019 17:24:22 -0400 Subject: [PATCH] iversion: add a routine to update a raw value with a larger one Under ceph, clients can be independently updating iversion themselves, while working under comprehensive sets of caps on an inode. In that situation we always want to prefer the largest value of a change attribute. Add a new function that will update a raw value with a larger one, but otherwise leave it alone. Signed-off-by: Jeff Layton Reviewed-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov --- include/linux/iversion.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/include/linux/iversion.h b/include/linux/iversion.h index be50ef7cedab..2917ef990d43 100644 --- a/include/linux/iversion.h +++ b/include/linux/iversion.h @@ -112,6 +112,30 @@ inode_peek_iversion_raw(const struct inode *inode) return atomic64_read(&inode->i_version); } +/** + * inode_set_max_iversion_raw - update i_version new value is larger + * @inode: inode to set + * @val: new i_version to set + * + * Some self-managed filesystems (e.g Ceph) will only update the i_version + * value if the new value is larger than the one we already have. + */ +static inline void +inode_set_max_iversion_raw(struct inode *inode, u64 val) +{ + u64 cur, old; + + cur = inode_peek_iversion_raw(inode); + for (;;) { + if (cur > val) + break; + old = atomic64_cmpxchg(&inode->i_version, cur, val); + if (likely(old == cur)) + break; + cur = old; + } +} + /** * inode_set_iversion - set i_version to a particular value * @inode: inode to set